Special counsel Robert Mueller’s Russia investigation has gathered enough steam that some lawyers representing key Donald Trump associates are considering the possibility of a historic first: an indictment against a sitting president.

While many legal experts contend that Mueller lacks the standing to bring criminal charges against Trump, at least two attorneys working with clients swept up in the Russia probe told POLITICO they consider it possible that Mueller could indict the president for obstruction of justice.

Neither attorney claimed to have specific knowledge of Mueller’s plans. Both based their opinions on their understanding of the law; one also cited his interactions with the special counsel’s team, whose interviews have recently examined whether Trump tried to derail the probe into his campaign’s Russia ties.

“If I were a betting man, I’d bet against the president,” said one of the lawyers.

The second attorney, who represents a senior Trump official, speculated that Mueller could try to bring an indictment against Trump even if he expects the move to draw fierce procedural challenges from the president’s lawyers — if only to demonstrate the gravity of his findings.

If we know anything about Mueller, we think we know that he follows the rules — all of them” — Paul Rosenzweig, former senior counsel in Clinton investigation

“It’s entirely possible that Mueller may go that route on the theory that, as an open question, it should be for the courts to decide,” the attorney said. “Even if the indictment is dismissed, it puts maximum pressure on Congress to treat this with the independence and intellectual honesty that it will never, ever get."

The lawyers’ assessments hardly resolve the public debate about whether a federal prosecutor can indict a sitting president — one that several attorneys involved in the Russia probe said they are closely tracking through online op-eds and Twitter dustups. (“It’s so much fun!” said one.)

Several legal scholars say an effort by Mueller to initiate a case titled U.S. v. Trumpwould, at a minimum, likely move quickly to the Supreme Court. There is no legal precedent for an indictment of a president — only a pair of Justice Department legal opinions, from 1973 and 2000 — saying it is not a viable option.

The 2000 opinion concluded that the indictment or criminal prosecution of a sitting president “would unconstitutionally undermine the capacity of the executive branch to perform its constitutionally assigned functions.”

The memo was written by an assistant attorney general nearly two years after the House impeached President Bill Clinton for lying under oath and obstructing justice about his affair with White House intern Monica Lewinsky.

Independent counsel Kenneth Starr never tried to indict Clinton. But Starr, who filed a damning report to Congress in 1998, considered the option — and even tasked his lawyers with preparing draft indictments, as well as a legal opinion asserting his power to charge Clinton.

“It is proper, constitutional, and legal for a federal grand jury to indict a sitting President for serious criminal acts that are not part of, and are contrary to, the President’s official duties,” Starr’s legal adviser, Ronald Rotunda, concluded in a 1998 memo first made public last summer through an open records request by the New York Times.

“In this country, no one,even President Clinton, is above the law,” the memo said.

Despite that assertion, Rotunda said in an interview that Mueller cannot indict Trump because he has a different legal standing than Starr enjoyed. Starr’s powers were defined by an independent counsel statute that expired in 1999. Rotunda said Mueller, by contrast, effectively has the powers of a U.S. attorney and must follow all DOJ “rules, regulations, procedures, practices and policies.”

That would mean Mueller is bound by the Clinton Justice Department’s 2000 memo, he said, as well as another Justice Department opinion written in 1973.

“If we know anything about Mueller, we think we know that he follows the rules — all of them,” Paul Rosenzweig, another former Starr deputy, wrote Tuesday in the Atlantic. “Mueller will not indict Trump for obstruction of justice or for any crime. Period. Full stop. End of story. Speculations to the contrary are just fantasy.”

The 1973 Justice Department memo was used toshield President Richard Nixon from a possible indictment by Watergate prosecutors, who believed they had the power to bring one. That debate was unresolved after the special prosecutor decided to share his work with the House judiciary committee, which was preparing to launch impeachment proceedings against Nixon.

The Justice Department regulations that govern Mueller’s work offer no clear endgame for the public to follow his investigation.

They do stipulate that the deputy attorney general, Rod Rosenstein, has oversight of and final say on all major decisions by Mueller — specifically including any indictments. Rosenstein is also required to submit a report to Congress on the grounds for closing the investigation.

Mueller’s office and the Justice Department both declined comment, as did attorneys for Trump and the White House.

In a December interview with Axios, Trump’s personal lawyer John Dowd argued that the “president cannot obstruct justice because he is the chief law enforcement officer" under the Constitution.

Some Republicans warn that Mueller would be playing with fire should he pursue an indictment of Trump.

"It would create a constitutional crisis," said Representative Ken Buck (R-Colo.), a former federal prosecutor and district attorney.

Buck said Mueller would be on especially dangerous ground were he to base an obstruction of justice case on Trump’s firing of FBI Director James Comey: “Assessing the motives" of a president who decides to dismiss executive branch personnel would be "unique in the history of the country,” he said.

Signs that Mueller is closing in on Trump have been growing for months. Mueller has indicted former top Trump campaign aides Paul Manafort and Rick Gates — both have pleaded not guilty — and obtained guilty pleas from former national security adviser Michael Flynn and former campaign adviser George Papadopoulos for lying to the FBI.

Witnesses and attorneys who have been interviewed by the special counsel’s team say the special counsel is focusing on a potential obstruction of justice case based on several well-documented events, including Trump’s firing of Comey and his efforts to prevent Attorney General Jeff Sessions’s recusal from the Justice Department’s Russia probe.

Their level of confidence has grown, and that’s a body language thing” — Attorney on Russia defense case

The lawyer who said he would “bet” against Trump said he thinks Mueller could wrap up his case soon, potentially with an indictment, to avoid acting too close to this fall’s midterm elections.

“If he’s going to do it, I think he’ll do it in the spring,” the attorney said. “I don’t think he wants to be accused of trying to influence the election that dramatically.”

On Capitol Hill, several Democrats said they believe Mueller has the authority to file charges against Trump but questioned whether he actually would.

"I think that it’s far more likely if the special counsel finds evidence of criminality... that it’s presented in a report to Congress," said Representative. Adam Schiffof California, the top Democrat on the House Intelligence Committee.

Schiff said Mueller would likely have steep reservations about the notion that "12 jurors in some part of the country should decide the fate of the republic."

In addition, Schiff said a federal judge might stay any criminal proceedings until after Trump’s presidency.

That was the assumption of the Nixon-era Justice Department memo, which suggested such an outcome could be disastrous.

“Given the realities of modern politics and mass media, and the delicacy of the political relationships which surround the Presidency both foreign and domestic, there would be a Russian roulette aspect to the course of indicting the President but postponing trial, hoping in the meantime that the power to govern could survive,” wrote Robert G. Dixon Jr., then an assistant attorney general and head of the Justice Department’s Office of Legal Counsel.

Rosenstein could also deny any attempt by Mueller to indict Trump. Justice Department rules would require such a denial to be transmitted to the House and Senate judiciary committee leaders at the conclusion of Mueller’s work.

Deuputy Attorney General Rod Rosenstein has final say on any major decision by Mueller | Zach Gibson/Getty Images

That scenario “would allow everybody involved — Mueller, Rosenstein — to play the thing strictly by the book and still get Mueller’s conclusion, if there is one, that the president committed a crime, into the hands of the only people to whom it really matters, which is Congress,” said Frank Bowman, a former Justice Department trial attorney and University of Missouri law professor.

Philip Allen Lacovara, who served as a top counsel to the two Watergate special prosecutors, said he believes Mueller could seek an indictment against Trump, but only if the facts suggest a “slam dunk” case against the president.

Lacovara dismissed the Clinton Justice Department memo’s contention that an indictment would interfere with the president’s official duties.

“When an incumbent president, whether it’s Bush or Obama or Trump, spends an enormous amount of time on the golf course, it’s a little bitfanciful to say the president can’t be called to account for alleged criminality because he’s got to be available 24 hours-a-day to be president,” he said.

One of the Russia defense attorneys also suggested what he called a “jujitsu move”: naming Trump as an unindicted co-conspirator in a larger obstruction of justice case that targets one or more associates.

Whatever Mueller and his deputies have planned, the attorney said, it is not likely to be anticlimactic.

“There’s a sense of confidence I feel when I’m with them,” said the same lawyer. “Their level of confidence has grown, and that’s a body language thing.”